1. Field
The subject matter disclosed herein relates to recovering unintentionally deleted data sets in a virtual storage access method (VSAM) system.
2. Description of the Related Art
Accidental deletion of data is going to happen in a data storage system, often because of human error. For example, an administrator managing a virtual storage access method (VSAM) system may unintentionally delete a data set in a volume. Once the administrator realizes her error, she has to rebuild the unintentionally deleted data set from backup sources. Depending on the size of the data set, this can be a time consuming task. And if the data set was not backed up properly, the data set may be irretrievably lost.
Accidental deletion is particularly painful if the data set is a VSAM volume data set (VVDS). A VVDS is a data set that describes the dynamic characteristics of VSAM and system-managed data sets residing on a given volume. The VVDS is part of the integrated catalog facility (ICF) and contains information about data sets on the volume. The VVDS is commonly used to provide attribute information so that, when opening or accessing a data set on the volume, the attributes of the data set are known. If the VVDS is accidentally deleted, the administrator typically has to rebuild the entire volume, not just one data set, in order to reconstruct the VVDS. The administrator will have to define a new VVDS and then recover all of the data sets that existed on the volume from backup data sources such as tape drives. This process of determining that the problem is a deleted VVDS, configuring the backup data sources, preparing the volume to be rebuilt, and transferring all of the data on the backup data sources to the volume, and then validating the restore operation is time-consuming. The resulting costs to an entity using the volume, in terms of time, money, and loss of data availability, can be very high. Furthermore, if the data sets were inadequately backed up, data may be lost.